1. Field of the Invention
This invention relates to modulated release aerosol particles, and more particularly, to medicinal aerosol particles comprising polymeric silicate vesicles which entrap a selected medicament and provide slow release thereof.
2. Description of the Related Art
Many drugs currently administered by inhalation come primarily as liquid or solid aerosol particles of respirable size. For biotherapeutic drugs, this may present a problem, as many of these medicaments are unstable in aqueous environments for extended periods of time and are rapidly denatured if micronized by high shear grinding or other commination methods when presented as dry powders. Additionally, a number of these medicaments do not survive long enough in the lung as they are extracted quickly from the lung environment after they are administered as inhalation aerosols. Significant drug loss could also occur by deactivation either as a result of reactivity of the medicament with device and container surfaces, or during aerosolization, particularly in high shear, energy intensive, nebulized systems [Mumenthaler, M., et al., Pharm. Res., 11: 12-20 (1994)].
To overcome these instability problems, many drug and excipient systems contain biodegradable carriers, such as poly(lactide-co-glycolides) have been developed for biotherapeutic proteins and peptides [Liu, R., et al., Biotechnol. Bioeng., 37:177-184 (1991)]. These medicaments, presumably, are adequately protected in their carrier systems, and thus do not undergo as much denaturation as realized in aqueous media. Importantly, these polymers prolong drug release at the site of absorption so that the effect of the drug is also subsequently sustained in the body.
Most therapeutic peptides and proteins are poorly absorbed through biologic membranes even upon formulation with penetration enhancers, possibly due to a combination of several factors, including large molecular size (i.e., xe2x89xa71000 daltons), ionization, high surface charge, enzymatic and chemical instability, and low permeability of absorption barriers in the body of a patient, e.g. human being or other animal. In numerous therapies, drug dosimetry is increased by orders of magnitude to achieve minimum systemic concentrations required for efficacy. In other cases the drug product is formulated with exotic absorption promoters in order to improve permeability across the absorption barrier. But such formulations usually present serious toxicological liabilities. The clinical and pharmaceutical chemistry sciences, in an attempt to accomplish the highest level of therapeutic benefit for these compounds, have resorted to chemical modifications as a principal mode for improving biological activity of these drugs in the body of the patient. The mode of drug administration to the body has also gradually expanded from oral and parenteral to transdermal, rectal and the pulmonary routes of administration, i.e., nose and lung. Success and achievement with these drug delivery approaches are mixed largely due to lack of acceptance of the newer, complex molecules that must be used for treating difficult diseases of the body, e.g., infections, malignancies, cardiovascular, endocrine, neurologic diseases, and a variety of immunologically compromised diseases, like AIDS.
Accordingly, what is desired and needed is a fluid propelled formulation system comprising an active pharmaceutical ingredient (xe2x80x9cAPIxe2x80x9d) that is stable and protected by a rate-limiting carrier, easily manufactured, and therapeutically effective when administered as fluid dispersed particles to the lung of a patient, e.g. a human being or another animal.
This invention relates to modulated release aerosol particles, and more particularly, to medicinal, respirable aerosol particles comprising polymeric silicate vesicles which are associated with, e.g. form a part of a construct with or entrap therewithin, a selected medicament and provide slow release thereof.